Undocument Prefix After Decrypting Outputs of a computation

[fredfortier]

Describe the bug
Decrypting the output of a computation includes a prefix, at least when he results are Vec<u8>. What is it used for?

To Reproduce
See example here: https://github.com/enigmampc/coinjoin-poc/blob/65350409f4dbf43eeb178904cec3ca25e7e5070e/enigma-coinjoin-operator/src/secretContractClient.js#L86

Let me know if you need more contexts. Hackaton participants have observed the same thing. They also had trailing zeros which weren't in the returned Vec<u8> variable.

Expected behavior
No prefix or an explanation of what the prefix means.